First description of the female of Sarcophaga (Sarcorohdendorfia) gracilior (Chen, 1975) (Diptera, Sarcophagidae)

Abstract Sarcophaga (Sarcorohdendorfia) gracilior (Chen, 1975) is documented from specimens collected in Hubei Province, China, using morphological characters and wing interference patterns (WIPs). The female of S. (S.) gracilior is described for the first time, the male is redescribed, and both sexes are photographed. The distribution of the species is updated.


Introduction
The Sarcophagidae (flesh flies) is a medium-sized family of Diptera with about 2600 known species worldwide, which includes various life history strategies ranging from inhabitants of pitcher plants to bat coprophages, crab saprophages, wasp nest inquilines, and insect parasitoids (Pape 1996). Some species are carrion breeders and therefore forensically important for the estimation of the time since death, i.e., the postmortem interval (Greenberg 1991;Catts and Goff 1992;Amendt et al. 2004), and several species of these flies have been recorded in association with human remains (Sukontason et al. 2001(Sukontason et al. , 2007Chaiwong et al. 2009;Cherix et al. 2012).
Sarcorohdendorfia Baranov is a large subgenus of Sarcophaga Meigen (sensu lato), and it currently comprises 61 species known mainly from the Oriental and Australasian/Oceanian Regions (Pape 1996;Meiklejohn et al. 2013;Whitmore et al. 2013). The species Sarcophaga (Sarcorohdendorfia) gracilior (Chen, 1975) was originally described (in Tricholioproctia Baranov) based on eight male specimens from the type locality Mt. Tianmushan, Eastern China. Chen (1975) established the subgenus Hamimembrana with S. gracilior as its type species and only member. Lopes and Kano (1979) treated Tricholioproctia as a junior synonym of Sarcorohdendorfia, and Pape (1996) considered Sarcorohdendorfia as a subgenus of Sarcophaga s.l., and listed the subgenus Hamimembrana as a synonym of Sarcorohdendorfia. Since its description, S. (S.) gracilior has remained unnoticed by the majority of the scientific community and has appeared in the literature mainly through brief citations and catalogue entries (Kano and Shinonaga 1994;Fan and Pape 1996;Pape 1996;Chen et al. 2010;Zhang et al. 2010). Besides, the morphology of the male had not been studied in detail and information on the female of this species was completely absent. During a distribution survey about flies of medical significance around Central China, we discovered three female specimens of S. (S.) gracilior, which to our knowledge represent the first record of reliably identified females. We herewith provide the first description of the female of S. (S.) gracilior, and a redescription of the male.
Wing interference patterns (WIPs) were recently introduced as a potential new character system of extremely thin insect wings , and it has at this time proven useful for the separation of species in Hymenoptera, Hemiptera and Diptera (Buffington and Sandler 2011;Hansson 2011;Simon 2012). It might be suspected to provide a useful tool for correctly associating male and female specimens in some Sarcophagidae, and finds support in ongoing studies (Zhang et al., unpublished), and we therefore provide WIPs for both sexes of S. (S.) gracilior. This is the first time that WIPs are applied to a flesh fly.
The primary aims of this article are: 1) to provide the first description of the female of S. (S.) gracilior and a redescription of the male, and 2) to provide the first data on WIPs for flesh flies as a potential tool in associating conspecific males and females.

Material and methods
Flies inhabiting forested areas in the mountainous region of the Hubei Province, China, were attracted by the viscera of grass carps (Ctenopharyngodon idellus) obtained from the local market. Viscera were kept frozen until needed, thawed and left to decompose for about two days before being deployed separately in traps consisting of open plastic containers (5.0 cm high, 10.0 cm in diameter). Flies that visited the bait during 1-2 hours from the time of deployment, were collected. Specimens were deposited in the Museum of Beijing Forestry University (MBFU), Beijing. Photographs were taken with a Canon 550D camera mounted on an Olympus SZX16 stereomicroscope. The methods applied to view and document interference colour patterns in the flies' wings followed  and . Image processing softwares used were Adobe Photoshop CS3 (Adobe Systems, Inc., San Jose, CA, USA) and Helicon Focus 3.2 (Helicon Soft Ltd, Kharkov, Ukraine). Terminology of adult morphology follows McAlpine (1981). Distributional data was mainly taken from Pape (1996), with additional records obtained from major entomological catalogues (Chen et al. 2010;Zhang et al. 2010). The single male specimen was identified using Xue and Chao (1998) and by checking against the original description (Chen 1975). The female specimens were identified through careful comparisons with the male, supported by the fact that one pair (male + female) was collected in copula.
Legs dark, with grayish black pollinosity; fore femur with one row of dorsal bristles, one row of posteroventral bristles and one row of posterodorsal bristles, fore tibia with four anterodorsal and one posterior bristles; mid femur with four median anterior, one apical posterior and one apical posterodorsal bristles, mid tibia with two anterodorsal, one ventral and one subapical posterior bristles, and with one row of First description of the female of Sarcophaga (Sarcorohdendorfia) gracilior (Chen, 1975)... 49 posterodorsal bristles (one strong); hind femur with one row of anterodorsal bristles, and with one apical posterodorsal and two apical posterior bristles, hind tibia with one row of anterodorsal bristles (among them three strong), and with one anteroventral and four posterodorsal bristles.
Thorax: fore femur with slender ventral setulae in basal 1/2, fore tibia with three anterodorsal bristles; mid tibia with one anterodorsal bristle; hind femur with one row of anterior bristles, and with one apical posterior and three apical posterodorsal bristles, hind tibia with two posterodorsal bristles, and with slender and dense setulae along anteroventral and posteroventral surfaces.
Abdomen long oval; epandrium black; sternites 1−4 with dense setulae, sternite 4 with a dark spot consisting of dense short setulae on posterior margin (see Chen 1975: fig. 5). Terminalia (see Chen 1975: figs 6-9): cercus straight in profile, with numerous  (Chen, 1975). A Male, right wing interference patterns, dorsal view B Male, right wing, dorsal view C Female, right wing interference patterns, dorsal view D Female, right wing, dorsal view. Scale bars = 2.00 mm E Schematic illustration of the distinctive clearly demarcated magenta and blue bands, and one large and almost triangular area on the apical part, which is blue in the WIP. Arrows in A & C show the most similar patterns and marginal colour bands of both sexes. strong setulae on mid lateral margin and with a sharp apex in lateral and dorsal view. Surstylus almost triangular but with a slightly convex anterior (or ventral) margin (Fig.  4B). Pregonite with a broad base, slightly longer than postgonite, and distal half almost perpendicular to basal half, postgonite long triangular with slightly curved apex; vesica large; juxtal extensions small with a sharp tip in lateral view; lateral stylus slender, with recurving teeth in the distal half and situated under the arched juxta (Fig. 4A). Other morphological characteristics are the same as for the female. Remarks. The specimens of this species have been taken in traps baited with fish viscera, indicating that this species may be saprophagous like the majority members of the genus Sarcophaga.

Discussion
Females of most species of flesh flies are very similar in appearance and difficult to identify (Ye 1992;Pape 1996;Xue and Chao 1998), which represents a problem, e.g., for forensic investigators, because most specimens collected at death scenes are gravid females or larvae. Correct identification of females in the large genus Sarcophaga is very important, as it would be a prerequisite for many detailed ecological studies (e.g., Bänziger and Pape 2004;van der Niet et al. 2011), forensic investigations (e.g., Cherix et al. 2012), or cladistic analyses (e.g., Giroux et al. 2010). Morphological studies of Sarcophaga spp. have traditionally focused on the male sex, but Richet et al. (2011) and Meiklejohn et al. (2013) showed females are fully identifiable in many cases. To facilitate the identification of females in studies including S. (S.) gracilior, we provide the first description of the female and bring further distributional records of the species in China.
WIPs may arise in transparent insect wings due to their double layer of very thin cuticle . The interference pattern caused by the ultra-thin but uneven wing membrane can be visualized against a dark background. WIPs have already proven to be of value in generic and even species-level identifications of several insect groups (Buffington and Sandler 2011;Hansson 2011;Simon 2012), and ongoing studies found WIPs to be species-specific and showing no sexual dimorphism in some taxa of Miltogramminae (Zhang et al. unpublished). We employed this method for comparisons between both sexes of S. (S.) gracilior, and the WIPs show no sexual dimorphism (Figs 5A, 5C). Studies of WIPs from other species of Sarcophaga are still needed to test if WIPs might serve as an appropriate way to confirm conspecificity of male and female specimens in the subfamily Sarcophaginae.